For thousands of years before the early Christians co-opted the observance of the winter solstice into Christmas, the pagans tracked the point on the horizon at which the sun rose and set. The winter solstice - the day on which the point of sunrise stopped moving southward along the horizon and began moving northward again (in the northern hemisphere) - was determined through repeated annual observation.
Strong alignment of elements in structures like Newgrange (constructed in Ireland around 3200 BCE), Stonehenge (England, between 3000-2000 BCE), and Maeshowe (Orkney, circa 2800 BCE) to the point where the sun rose on the winter solstice evidenced a high degree of awareness to this important seasonal turning point by early human societies.
The winter solstice appears to be among the earliest cosmological phenomena observed by humans, predating written religious texts, formal theology, or mathematical astronomy.
In the Roman calendar during the early days of Christianity, December 25th was celebrated as the date on which the days began to lengthen again. Christians were quick to appropriate this date as the day of Christ’s birth even though the New Testament gives no date for Jesus’ birth and the early Christians treated Easter and the resurrection (determined to be in late March in the Roman calendar) as a much more important date. However, It was expedient to re-interpret, compete with, or absorb the existing popular pagan winter festivals into what became Christmas. By the mid-fourth century, December 25th was firmly established as Christmas in Rome.
But with advent of more sophisticated observational and mathematical astronomy, we now know the date of the winter solstice is 21 December.
Here in north central Colorado it is the dark, not the cold, that affects me the most. Having dinner several hours after sundown, thinking it is almost time for bed, and looking at the clock to realize it is only 7:30 pm is tough. In December, the sun appears at the southern shoulder of the mountain to my east, slides along the horizon behind the tall Ponderosa Pines, and then disappears again behind another peak to the south.
So I pay close attention to its changing trajectory as it appears a little earlier and a little higher each morning in my east-facing window. Until finally in the Spring it never hides behind that eastern mount at all - it climbs above the valley way to the north, clears the hills and the pines, and finally descends behind the ridge to the west.
So here is a composition celebrating the turning point that is the winter solstice. We still have months to go before the hummingbirds return, the wildflowers bloom, and the days are long - but the trend has begun.